1. Field of the Invention
This invention relates generally to the design of an electrosurgical scalpel, and more particularly to a bipolar scalpel having specially designed electrodes for facilitating cutting of tissue without the need for an expensive blade of the type heretofore used in prior art bipolar scalpels.
2. Discussion of the Prior Art
In U.S. Pat. No. 4,161,950 to Doss, et al., there is described a knife blade for an electrosurgical scalpel which comprises a thin blade substrate whose periphery is honed to a sharp cutting edge and which carries first and second conductive electrodes adjacent to that cutting edge. The substrate is preferably ceramic and the electrode traces are deposited on the ceramic using known metalizing techniques, wherein a metal powder containing slurry is applied to the substrate through a mask and then later fired to bond the metal to the ceramic substrate. Blades of this type suffer from a number of drawbacks, not the least of which is the cost of producing same. The processing steps involved, including forming the blade substrate, honing its edges, depositing metal conductor traces thereon and subsequently selectively coating the blade surfaces with an insulating material, makes the resulting product relatively expensive, especially, and as will be explained more fully hereinbelow, when contrasted with the present invention.
Blade configurations, such as shown in the Doss '950 patent and in U.S. Pat. No. 4,232,676 to Herzog, suffer from other defects, including breakage and the inability of the electrode foils to withstand the high temperatures resulting when arcing occurs between the active electrode surface and its return electrode.
It is accordingly a principal object of the present invention to provide an improved bipolar electrosurgical scalpel instrument.
Another object is to provide a bipolar electrosurgical scalpel instrument having a low-cost "blade" element which is sufficiently strong to withstand mechanical forces encountered during manufacture, shipping and handling and during use in surgery.
A further object of the invention is to provide a variety of electrosurgical scalpel blade configurations which can withstand elevated temperatures resulting when an arc breakdown occurs between electrodes over prolonged periods of use.
Yet another object of the invention is to provide an electrosurgical instrument having both cutting electrodes and coagulating electrodes where the cutting electrodes are retractable and, when retracted, allow the coagulation electrodes to be used.
Another object is to provide an electrosurgical instrument that can be controlled to operate in either a "cut" mode or a "coag" mode, either by a foot switch or by placement of a thumb-operated switch.